Sep

24

A recent Wall Street Journal article discusses findings that children born in the winter do worse in school and earn less than children born at other times of year. The first reaction was to search for environmental factors. Did lack of sunlight in infancy cause lasting damage? Did being in the same grade with younger students limit achievement?

Further research showed that heredity might play a role. Births to highly educated women peaked in May each year, while births to less educated women peaked in January. The likelihood that a woman giving birth was married was 2 percentage points less in January than May.

Nigel Davies reacts:

I learned recently that 75% of a child's IQ is from the mother, so it may be purely an IQ thing. As May minus 9 months = September maybe smart women tend to schedule their baby production after their summer holiday!?

David Wren-Hardin queries:

I read the same article, and saw nothing in there about heredity playing a role. It did say, as you say Steve, that the winter-born babies tend to be born to less-educated women. Education is, obviously, something someone does, not something someone inherits.

And to Nigel: Who told you 75%?!

Nigel Davies replies:

A reliable source.

Alex Castaldo adds:

I think I could guess the source's gender.

Gordon Haave is not amused:

Obviously none of you have read The Bell Curve by Richard Herrnstein and Charles Murray.

David Wren-Hardin comments:

I've read parts of the book. There are some interesting conclusions, but they fall far too far on the intelligence is pre-determined and we can do nothing about it spectrum. Are we blank slates? No, but our intelligence is highly tuned by our environment. That's actually great news — we don't have to simply accept that some people are "stupid", shrug our shoulders and move on. Everyone can become smarter and realize more of his potential.

More and more study is showing that IQ is much more malleable to environment than previously thought. For example, twin-studies had been used to state that IQ must be inherited since twins raised in different environments have similar IQs. However, once you control for the selection bias in adoptive parents — people who adopt tend to be more highly educated and have more resources — a great deal of the "heredity" effect goes away. It's still there, just not as strong as previously assumed.

There have also been studies showing how the "culturally unbiased" tests, the ones that are supposed to tease out untaught learning from innate intelligence, are actually highly affected by previous exposure to various spatial concepts.

Yishen Kuik summarizes:

From what I remember about studies of intelligence, the key findings were:

1) The correlation of IQ scores by adopted siblings & their natural siblings was 0.0 (ie no different from strangers), whereas those between natural siblings was about 0.6.

2) The correlation of IQ scores of monozygotic twins separated at birth was 0.9 vs dyzygotic twins raised together at 0.6.

Those were the strong conclusions used to argue that environment had far less impact on how well someone scored on an IQ test, compared with their natural endowment. (Note that this does not imply they inherited their intelligence from intelligent parents). How does Prof. Nisbett's findings about cultural biases or the fact that adopters tend to be well educated / wealthier alter these findings?

Stefan Jovanovich writes:

This may not answer Yishen's question directly, but what follows is the sum of what my father told me about IQ tests. Dad had, I think, some credibility on the subject; he made his fortune from running the only for-profit publisher who competed successfully with ETS. He was also smart enough never, ever to voice these opinions to anyone until the year and a half before his death when he decided that he would indulge himself in the luxury of telling himself and anyone who would listen the absolute, unvarnished truth about what he knew from half a century in the book and test trades.

1) IQ tests are unpopular precisely because they are brutally honest and cannot easily be rigged. No one likes their results. The students hate them because they show us all how rare exceptional intelligence really is. The teachers hate the IQ tests because they find that the brightest students are most often not the diligently obedient pupils who copy down everything the teachers say and repeat it back to them on the exams. Instead, the tests suggest that really bright people are unruly and more interested in their own thoughts than other people's. The parents hate them because the test results shout that money alone cannot buy brains. The school boards and administrators hate them because the test results indicate that most of the time spent in class is utterly wasted.

2) There are only three reliable correlations between inputs and measurable academic achievement — the IQ of the child, the IQ of the parents and the IQ of the teachers. Every other metric — class size, spending per pupil, curriculum models (new, new vs. old, old math) have not statistical importance. Dad would hardly have been surprised by Dr. Nisbett's findings since the IQ of adoptive parents is significantly higher than the general population. He would, I think, have disagreed strongly with the assertion that "a great deal of the 'heredity' effect goes away." By far the most important single cause of success was the IQ of the child.

David Wren-Hardin replies:

I agree with most of what you said earlier; IQ is measurable, and people don't like that. What I want to add is that it is modifiable. But past certain points, it may not make a difference on life outcomes. Other traits, such as persistence and the ability to delay gratification, may have greater effects.

I'm not going to speak for Dr. Nesbitt, but on this last point I'd say that the child's IQ has already been set by the environment he came from. My argument doesn't necessarily help the education debate, it may, in fact, it may make it bleaker: Compared to the effect of a child's surroundings in his early years, public education comes in with too little, too late. "Low IQs" are still the parents' fault, but not necessarily because of genetics.

But the take home message to me, and what I tell my kids, is that they can always be better at something than they are now, if they apply themselves at the limits of their ability.

Stefan Jovanovich sums up:

Dad would certainly have agreed with David. He thought that modern teachers' refusal to "teach to the test" was an indication of how corrupt education had become. IQ can be "taught" in the same way that people learn alphabets and sums; be repeated trial and error — taking tests again and again. It appalled him that school was made over into something that was "fun" and "self-discovery." Learning was work, and that is why the students should be paid for their results, even as early as kindergarten. That would, Dad thought, teach persistence and the ability to delay gratification — which, as David notes, are "lessons" that are vital to the growth of human happiness and accomplishment.